The Trump administration this week summarily dismissed more than 400 scientists and other experts who had begun to write the latest National Climate Assessment report, informing them by email that the scope of the report was being reevaluated.

The report, mandated by Congress, is prepared every four years under a 1990 law. It details the latest science on climate change, and also reports on progress in addressing global warming.

Scientists said they fear the Trump administration could seek to shut down the effort or enlist other authors to write a very different report that seeks to attack climate science — a path they say would leave the country ill-prepared for worsening disasters intensified by humanity’s warming of the planet, including more intense heat waves, wildfires, droughts, floods and sea-level rise.

“Climate change puts us all at risk, and we all need this vital information to help prepare,” said Katharine Hayhoe, a climate scientist at Texas Tech University who was an author of four previous versions of the report, including three times as a lead author. “Without it, the future will be much more dangerous.”

The Ohio River floods the Riverwalk in Smale Riverfront Park, Wednesday, April 9, 2025, in Cincinnati.

(Carolyn Kaster/Associated Press)

She noted that although the assessment is required by law, there aren’t specific requirements about who exactly should write the report or the form it should take.

“It could end up being a collection of long-debunked myths and disinformation about climate change,” Hayhoe said. “It could end up being a document that is just not useful, does not serve the purpose of providing information to the American people on the risks of climate change and the best ways to mitigate or adapt to those risks.”

Trump administration officials didn’t respond to requests for comments.

Participants in the latest study, set for release in late 2027 or early 2028, received an email Monday informing them they were being dismissed.

“At this time, the scope of the [report] is currently being reevaluated,” said the email from Heidi Roop, deputy director for services of the U.S. Global Change Research Program. “We are now releasing all current assessment participants from their roles.”

It thanked them for participating and said that “as plans develop for the assessment, there may be future opportunities to contribute or engage.”

The report is prepared by scientists and experts who volunteer their time. They were working on what would be the sixth assessment since the first report came out in 2000.

“The National Climate Assessment is a national treasure,” said Costa Samaras, a professor of civil and environmental engineering at Carnegie Mellon University who had been working as the lead author of the chapter on climate change mitigation prior to Monday’s announcement. “It is accessible, supported by the highest levels of scientific integrity, and represents the best available science to the American people on how their communities are changing because of climate change, and how they can respond.”

The report’s update comes at a critical time, as the burning of fossil fuels and rising greenhouse gases put the Earth on a trajectory for a climate that is warmer and more volatile than humans have experienced. The most recent National Climate Assessment, released in 2023, detailed the latest science on more extreme heat waves, wildfires and other disasters, and said that without deeper cuts in emissions and faster adaptation efforts, “severe climate risks to the United States will continue to grow.”

Last year, the United States experienced 27 weather and climate-related disasters that each measured at least $1 billion dollars in losses — costing the country $185 billion in total, according to the National Oceanic and Atmospheric Administration. Over the last five years, there have been 115 separate events that cost communities more than $750 billion.

“The National Climate Assessment helps communities understand how climate affects their population, their ecosystem, their infrastructure, and helps them prepare and adapt to these changes,” Samaras said.

A man looks on at the destroyed KEP Electric building after a tornado passed through an industrial industrial park on April 3, 2025, in Jeffersontown, Ky.

(Jon Cherry/Associated Press)

He said his team had been making good progress on their chapter, which is meant to take stock of how well and in what sectors the United States is reducing the greenhouse gas emissions that drive global warming, as well as what innovation opportunities exist for the country to grow industries that will help produce clean energy. They had already onboarded all of their authors — which included federal government employees and researchers from academia and nonprofits — and submitted a preliminary draft for review.

“It’s a huge loss,” Samaras said. “It’s a loss for taxpayers, it’s a loss for communities, it’s a loss for the environment. Not producing the report saves us basically nothing and costs us maybe everything.”

Ladd Keith, an associate professor of planning and director of the University of Arizona’s Heat Resilience Initiative, also received the email. Keith said he and other contributors were carefully selected to ensure a range of scientific expertise and regions were represented.

“If a report is provided to fulfill the Congressional mandate without the expertise of the contributors and a rigorous and transparent peer review process, it will further erode the credibility of this administration’s ability to address our nation’s most serious and pressing challenges,” Keith said.

“The hottest ten years on record were all in the last decade, and the U.S. is experiencing increases in extreme heat, drought, wildfire and flooding,” Keith said. “Losing this vital source of information will ultimately harm our nation’s ability to address the impacts of climate change.”

Trump and his administration have repeatedly criticized, undermined and defunded science on climate change. While seeking to boost oil and gas drilling and production, the Trump administration has fired thousands of government scientists and canceled many grants that had supported climate research.

Federal scientists recently were ordered not to attend a meeting of the U.N.’s Intergovernmental Panel on Climate Change. And in early April, the administration terminated a contract with a consulting firm that had supported technical staff at the U.S. Global Change Research Program, which coordinates federal research and the writing of the National Climate Assessment.

Project 2025, the conservative blueprint written by Trump’s allies last year, advised the president to review and possibly reject the program’s assessments.

“The next President should critically analyze and, if required, refuse to accept any [U.S. Global Change Research Program] assessment prepared under the Biden Administration,” the document says.

It argues that the National Climate Assessment and other climate change research programs reduce the scope of the president’s decision-making powers and that of federal agencies. It also says the process should include more diverse viewpoints. Both are themes that have played out repeatedly in the first 100 days of the second Trump administration, which has focused on rolling back environmental regulations and reducing bureaucratic red tape in the name of cost savings and greater U.S. energy independence.

“Everything we’ve seen in their first 100 days is just cause for alarm when it comes to climate science,” said Rachel Cleetus, an economist and policy director of the Union of Concerned Scientists’ climate and energy program. “The motivations are clearly to privilege fossil fuel interests over the interests of the public. This report is entirely in the public interest, and they’re just trying to bury the facts.”

Cleetus had been among the authors of a chapter on how climate change is affecting U.S. coasts.

Edward Carr, senior scientist and director of the Stockholm Environment Institute’s center in the U.S., said the report’s cancellation is “another effort to erase the evidence on which serious policy debate can be constructed.”

The Trump administration also recently canceled the writing of a major scientific report called the National Nature Assessment, which began under the Biden administration.

“The pattern that I’m seeing across the federal government is acting as if eliminating all mention of climate change will make climate change go away, which is certainly not correct,” said Chris Field, director of Stanford University’s Woods Institute for the Environment.

Field was an author of the nature assessment report before it was shelved, and has also been an author of previous versions of the climate assessment.

He said if the next version of the report is scrapped, the country would lose up-to-date and authoritative information from the federal government, which has been widely used to inform local decisions by cities, states, planning agencies, flood control authorities, coastal commissions, and agriculture agencies, among others.

Without such information, the country will be less prepared for the effects of climate change that are ongoing and increasing, he said.

“It’s as if, when you’re driving your car, you have half the window blocked out, or your headlights don’t work,” Field said. “The ability to make good decisions about the future really depends a lot on the best available information, and cutting off access to that information, making it more difficult to get, makes life more challenging, uncertain and expensive.”